In order to improve the riding quality of a railway vehicle, it is essential to accurately evaluate vibration and acceleration, which variously change depending on conditions of railroad tracks and vehicles, from the viewpoint of passengers. Such evaluation could be made by carrying out a running test, by means of an experimental vehicle, between runs by commercial vehicles. In this case, however, some problems arise as follows.
First of all, it is not easy to equalize the conditions of vehicles and tracks all the time running tests are performed, and reproducibility is not good. This fact results in a low reliability of evaluation. Also, it is difficult economically, and in view of efficiency as well, to shorten an interval of running tests or to carry out running tests a number of times. This fact results in a long period of development. Furthermore, it is not easy to modify conditions such as performance, properties, and the like.
On the other hand, there is known a system for simulating the riding quality without relying upon such running tests by use of experimental vehicles; that is, a simulation system by means of a simple four-axis vibration table for generating vibration along an up-down axis, a left-right axis, a forward-backward axis, and a roll axis (i.e., rotary motion about the forward-backward axis) (for example, refer to p.p. 113 to 116 of Ergonomics, vol. 33, 1997) This simulation system is capable of simultaneously generating vibrations along a plurality of axes arbitrarily selected among the four axes. According to such a simulation system, the aforementioned problems with the running of the experimental vehicles could be resolved.
However, no system for simulating lateral steady acceleration, which is generated when a railway vehicle runs around a curve, has yet been known.
Such a lateral steady acceleration simulation system could be realized by utilizing acceleration generated by moving a simulated passenger room in the left or right direction. In the case of a long-distance curve, however, a railway vehicle is subjected to the lateral steady acceleration for a long period of time. In order to simulate such a long-period lateral steady acceleration, extremely long rails extending in the left and right directions are required. This means that the size of the entire system needs to be large.